I understand that std::string str(std::istreambuf_iterator<char>(t),std::istreambuf_iterator<char>()) is a declaration of plain function, why the output of the code snippet blow
is

1

1

other than an address of a plain function, say

0x4591

0x4591

Here is the aforementioned code snippet:

#include <string>
#include <fstream>
#include <streambuf>
#include <iostream>


std::string str(std::istreambuf_iterator<char>(t),
                 std::istreambuf_iterator<char>()){
            return {};
};

int main()
{
    std::cout << str << std::endl;
    std::cout << &str << std::endl;
}